If the mean distance for the data set is much smaller than the one for CSR (COMPLETE State Randomness), the points tend to cluster.

Geological maps containing lithological and major structural information were also prepared digitally, in order to utilise these maps along with Potential SHP and earthquake epicentre locations for better planning and development (Figure 5). Digital base map and all potential site attribute information were integrated in the SPANS GIS to perform various types of queries / questions provided by the users / potential developers. The major advantage of such integrated GIS spatial database is that any new and relevant information with individual SHP can be brought into the system and further improved analysis can be performed with minimum efforts (Figure 6).


Figure 5

Analysis of Remote sensing data
Initially it was thought that various information such as catchment boundaries, main channe, habitation, concentration, road network etc. can directly be gathered from remote sensing data, however, later on it was realised that the data available from IRS-1A, 1B (LISS-III) sensors are not good enough for all requisite parameters for identification and confirmation of potential small hydro site . Though it is not difficult to identify catchment boundary and main channel in the remote sensing data in order to have other information related with small hydro, particulary for slope along main channel for potential head identification, name of the channel, location and name of the villages etc. Topographical maps of the area have to be referred and hence, it was decided to use remote sensing data of only those areas for which SOI 1:50,000 toposheets were not available.


Figure 6

It is true that in last two decades remote sensing has a powerful tool for any work related with natural resources and environment, however, in the present project the study area coverage was enormous and complete satellite coverage would require more than 200-LISS-II scenes. Further, the study area is an high altitude terrain, and hence perennial cloud and associated shadow problems and snow cover makes it difficult to get cloud-free and snow-free scenes.

GIS application in alternate sites identification
As discussed above that GIS is a very powerful analysis and data management systemand can also be utilized for various purposed e. g. spatial and non-spatial analysis cluster analysis, alternate site selection etc. Alternate site selection analysis using GIS has been performed in a sample area in Darjeeling tea estate area (Rungsun Khola catchment). Contour information using SOI 1:50,000 topographic maps were digitized and DEM of the Rungsung Khola has been overlaid on the DEM. Some proposed channels within one tea estate boundary were also overlaid on the DEM and drainage information. This overlay procedure provided slope information / available head along the Rungsung Khola. Applying certain constrains four alternate sites were selected (Table 3) which provides various options and available potential power etc. Using DEM catchment characterization has been performed and catchment boundary, stream slope calculation were determined .

Table 3: Various alternatives are provided on GIS based analysis for SHP planning purposes in Rungsung Khola catchment of Darjeeling tea estate area

Rungsuns Khola-I Discharge = 0.5 Cumec

Alternative	Channel Length (Km)	Penstock (m)	Head(m)	Power(kw)
1	1.50(Ch-1)	1.25	140	490
2	1.75(Ch-2)	0.50	100	350

Rungsung Khola-II Discharge=0.3 cumec

Alternative	Channel Length (Km)	Penstock (m)	Head (m)	Power (kw)
1	0.75 (Ch-3)	1.25	140	490
2	0.65 (Ch-4)	0.50	100	350

Combined (Khola-I + Khola-II)

Alternative	Channel Length (Km)	Penstock (m)	Head(m)	Power(kw)
1	2.25 (Ch1+3)	2.5	480	980
2	1.75 (Ch2+4)	1.0	200	700

Conclusion
As discussed above that integrated approach of GIS and RS can play very important role in the field of SHP planning and development. With the development and availability of fast and efficient computer and hardware and software GIS and RS tools are going to have more vital roles in natural resources development and environment. The spatial database which has been developed under the UNDP-GEF-HPP programme can further be augumented with new sets of data on meteorological, socio-economic and environment to support planning and decision making processes.

Acknowledgement
The author wish to acknowledge with gratitude about the cooperation received from the faculty and staff of AHEC, DES, CED, and NIH for conducting an study under an assignment from UNDP-GEF-Hilly Hydro Project, Ministry of Non-conventional Energy Sources, Govt. of India. The authors thanks for the kind permission to UNDP-GEF HH Project and Director AHEC for allowing the presentation of the study.

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